Minnesota Plant Diseases. 65 



tacks the grain from without while the latter is still very young. 

 It seems to be able to penetrate the grain coats at this stage 

 and immediately proceeds to convert the grain into storage 

 material, packing it up in the dark-coated storage organ known 

 as the ergot. This is used in the following spring to produce 

 the spore-bearing organs. The fruit-inhabiting fungi include 

 members of almost every group of fungi. Fruit-mold rots, 

 smuts and ergots have already been mentioned. There are 

 many other burnt-wood fungi beside ergot. Plum-pocket 

 fungi, cup fungi and algal fungi are also among the inhabitors 

 of fruits. 



Anther-inhabiting parasites. Among the smut fungi are to 

 be found forms which have developed very strange habits. One 

 of the most remarkable cases is that of the smut which forms its 

 spores only in the anthers of particular kinds of plants. The 

 latter are members of the pink family. The fungus gains en- 

 trance to the plant before the flower is completely formed and 

 in the young flower it selects for its abode only the stamens, 

 and particularly the pollen-bearing part or anthers. It gives 

 no external evidence of its presence until the flower opens. 

 \Yhen this happens one finds that, in place of pollen, the an- 

 thers give forth a violet dust of smut spores, and few, if any, 

 pollen grains are produced. To the casual observer such 

 flowers appear to throw off purple pollen while other flowers 

 of the same kind of plant give off yellow pollen. The fungus 

 has formed its spores in place of the host's pollen, and when 

 the anthers open they shed the spores. When insects visit 

 these flowers they carry smut spores in place of pollen from 

 plant to plant, thus aiding in the spread of the fungus. These 

 fungi often prove troublesome pests on plants of the pink fami- 

 ly, such as carnations, where the flowers are grown for show 

 plants, because the presence of the fungus cannot be foretold 

 before the opening of the flower, and after the latter event the 

 smut spores discolor the flowers so that they are worthless for 

 the market. It can readily be seen that this fungus has car- 

 ried to a remarkable degree of efficiency its selective power, 

 having learned not only to repress its spore formation until a 

 most favorable moment but also to choose a most advanta- 

 geous special floral part for the spores. 



